FIG. 7.

Autofermentative metabolite excretion from glycerol-adapted WT+G (⋄) and nifJ+G (□) cultures. Lactate, alanine, and acetate concentrations were determined by ¹H NMR. H₂ in the headspace was measured by gas chromatography. The nifJ+G cultures excreted 1.6-fold more lactate and 1.7-fold more succinate than the WT cultures, demonstrating the redistribution of carbon from acetate to these alternative pathways. Alanine excretion results were not significantly different between WT+G and nifJ+G cultures. The H₂ production by nifJ+G cultures was decreased 3-fold compared to WT+G culture results. The ordinate gives the concentrations per 10¹⁷ cells. Error bars represent ± one standard deviation as calculated from the results of three biological replicate experiments.